[FA-misc] Mass transit overhaul, needs testing and review

FictionArchive.Service.Shared/MassTransit/Contracts/JobStateChangedEvent.cs

@@ -0,0 +1,18 @@
+using NodaTime;
+
+namespace FictionArchive.Service.Shared.MassTransit.Contracts;
+
+/// <summary>
+/// Published by sagas on state transitions for centralized job tracking
+/// </summary>
+public record JobStateChangedEvent : IEvent
+{
+    public Guid JobId { get; init; }
+    public required string JobType { get; init; }
+    public required string FromState { get; init; }
+    public required string ToState { get; init; }
+    public string? Message { get; init; }
+    public string? Error { get; init; }
+    public Instant Timestamp { get; init; }
+    public Dictionary<string, object>? Metadata { get; init; }
+}